Art of making bisalkyl-xanthogens



properties.

ALBERT 'ROTHMANN, or nnrnnnenne, AND nnnmu'r s'rnm, or

M, assronous no or. Bonnnmenn a seamen o. in. a. n, or

WALDEOF, GERRY.

' 0F BIS I i:

no Drawing. Application fileaDeeember 12, 1924, Serial No. 755,555, and in Germany January 28, N24.

' This invention relates to the art of manufacturing bisalkyl-x'anthogens (oxy-alkyl thio-carbonic acid disulfides) which have been shown to possess valuable therapeutic They are distinguished by antiparesitic action and have been found to be particularly valuable for preventing and curing scab, itch (scabies and 'acarustch) andmange to which dogs and other animals are subject. However, I their employment for such pur oses, has been found objectionable or 'fiicult because the bisalkylxanthogens hitherto reduced are characterized by a disagreea le pungent and acrid ,7 that it has not been possible, heretofore, to

obtain them in chemically pure condition.

Thus the bisethyl-xanthogen obtained according to the directions given in Annalen der Chemie und Pharmacies, vol. 72 (1849) page 5 possess a biting and pungent odor while bispropyl xanthogen prepared accord ing to Gazzetta Chimica Italiana, vol. "17 (1887) p. 80, is characterized by an unpleasant, sharp, resinous smell.

It is the object of the present invention to. obtain theseproducts in a purified condition and to free them from the disagreeable odors and we have found in the course of our. experiments and investigations that a bisalkyl-xanthogen which is. free from all disagreeable pun out and acrid odors, and

'- whichis substantially odorless or, more enerally speaking never possesses more tian a weak, mild-,gester-like odor, free from disagreeable srnells associated withthe known product, can be obtained by subjecting the crude bisalkyl-xanthoglens, prepared according to the methods eretofore known, to the. action of a strong current of an-indifamt gas such as. air or steam. This treatment we carry out by steam current through the bisalkyl-Xanthogen in a liquid, dissolved or suspended condition at ordinary or raised temperature and, in certain cases,'in vacuo.

The purification of these compounds may also be advantageously attained by mixing 1 an iindifi'erent gas, such as air or steam,

with chlorine-gas employed for oxidizing alkali-alkyl-xanthogenates. In this case the urified bisalkyl-xanthogens, are obtained directly in an odorless or agreeably smelling condition,

odor, which is undoubtedly due to the fact passing the air or- One hundred parts by weight of MANNIM- The following examples embody the pre-' 5 carrying out our inven potas-" i I sium eth lxanthogenate as -obtained by methods one thousand parts by volume of water. Through this solution cooled to the term 1 perature of ice a strong current of air contammg'from about 5 to 10 percent of chlorine gas is passed. This treatment with air and chlorine results in the immediate preline form and it is continued until a sample itherto known are dissolved in cipitation of bisethyl-xanthogen in crystalof the residual watery liquidwhen treated with cupric sulfate will yield no further precipitate of copper-xenthogenate.

and freed from the adhering liquid by suction. The thus dried precipitate remain-l ing on the filter is then dissolved in ether;

In order to remove such small quantities of This crystalline precipitate is placed on the filter water as still remain in the mass after the above suction-filtration, a suficient amount of dehydrated sodium-sulfate is added to the solution of the precipitate in ether, whereby any small'quantities of water still. remaining are bound after the lapse of 'several hours. The amount of sodium sulfate thus added varies-according to the degree f of moisture, about 10 grams of sulfate thus added having been found suficient in most cases. After the completion of this dehydration the ether solution is freed from the sodium sulfate by filtration and the ether is distilled oil from the filtrate. The resi due forms alight-yellow oily liquid which sQOn'solidifies to a crystalline mass whose melting point is between 31 and 33, and approximating tinguishes it new the product hitherto obtained and havinga melting point of 27 to 28, centigrade, This new purified-prod uct is readily soluble in ether, in carbontetrachlorid and in benzene, and soluble v with difiiculty in cold alcohol. In contradistinction to the product hitherto obtained and described itis almost odorless, and free from all disagreeable pungent or acrid 32, centigrade, which dis- 9 odors. The fact that its melting point is much higher than that of the product heretofore known, for which a melting point of 27-28, C. is given confirms the assump tion that the former product was impure. By our process it has for the first time been obtained ina pure state.

Ewample 2.

at 35 millimeters pressure and in a current of steam. The process of distillation is continued until the oily liquid remaining 1n the still has lost its pungent smell. The bisethyl-xanthogen is then separated from said oily residue by the usual methods. The properties of the new product thus obtained are the same as those enumerated for the product of Example 1.

- Ea:am ple 8.

Crude bisethyl-xanthogen having a penetrating pungent odor is dehydrated and then brought into a high cylinder or receptacle and therein subjected to the action of a current of dry air which is passed through the oily liquid until the penetrating pungent odor hasdisappeared. A product is thus 0btained which has all of the properties of the product of Example 1.

Example 4.

Crude bispropyl-xanthogen prepared by the action of chlorine on propylxanthogenate of potassium and which is characterized by the pungent resinous odor is covered with a layer of water of several times I its volume and subjected to a strong current .chlorid and benzene of air at a temperature of about centi ade. The stream of air is passed through t e oily material treated until a sample of the same is free from any pungent odor. The product so obtained, the purified bispropyl-xanthogen, is'yellow in color and has a pleasant ester-like odor. After the action of the air current has ceased it is separated from the water and dried.

It is readily soluble in water, carbontetrabut dissolves with difficulty in cold alcohol. It is liquid at ordinary temperatures.

It will be observed from the foregoing that in all cases our process of purifying bisalkyl-xanthogen, whether it be the crude ro'd'uct on the market or described in the iterature, or the substance as it is being formed or generated in the course of treating an alkyl-xanthogenate with chlorine, involves as its primary characteristic the action on the said bisalkyl-xanthogen of an indifferent gas or gaseous agent, under which term, wherever used, we include air and steam. It will also be noted that under our invention the bisalkyl-xanthogen may be acted on alone in a liquid condition or combined with water that is to say, dissolved or suspended in or otherwise brought together with water.

What we claim and desire to secure by Letters Patent is:

1. The process of purifying an impure bisalkyl-xanthogen which consists in passing a current of an indifferent gaseous agent through the same.

2. The process of purifying an impure bisalkyl-xanthogen which consists in passing a current of air through the same.

3. The process of purifying bisalkyl-xan thogen which consists of subjecting the same to the action of an indifferent gas as it is being generated.

4. The process which consists in passing a current of an indiflerent gas through impure bisalkyl-Xanthogen combined with water.

5. The process which consists in passing a current of air through bisethyl-xanthogen as it is being generated.

6. The process which consists in passing a current of air through impure bisethylxanthogen combined with water.

7. The process which consists in passing a current of an indifferent gas through impure bisalkyl-xanthogen in vacuo.

8. The process which consists in passing a current of an indifferent gas through impure bisethyl-xanthogen combined with water in vacuo.

9. The process which consists in passing a current of an indifferent gas through inipure 'bisalkyl-xanthogen combined with water and heating the whole.

10. As a new chemical product, purified bisethyl-Xanthogen which is odorless, readily soluble in ether, carbontetrachlorid and benzene, diflicultly soluble in cold alcohol and Whose melting point is between 81 and 33, and approximating 32, ccntigrade.

In testimony whereof we hereunto .a'fiix our signatures ALBERT ROTHll'L-XNN. HELMUT STEIN. 

